It’s Still a Rare Earth
September 25, 2011
Now that hundreds of extrasolar planets are known, how do they compare to ours? The Kepler spacecraft has found a varied assortment of all sizes and distances away from their parent stars. Only a few reside in their star’s habitable zones. But that’s only the first of many requirements for life. Two recent studies indicate that Earth remains a rare bird in the celestial aviary.